Biological waste in the form of liquids and suspensions is produced e.g. in hospitals, agricultural or biological research and production facilities, plasma fractionation facilities, etc. Biological wastes produced in such facilities cannot be directly conducted to a sewer system, as these wastes often contain micro-organisms, such as bacteria, viruses, germs and the like, which are hazardous to humans and animals. Prior to conducting to a sewer system, such biowaste must first be deactivated in a treatment plant designed for this purpose. For the treatment of biowaste, different treatment plants have been designed in which biowaste is sterilized prior to conducting to the sewer system. The sterilization of biowaste can be carried out chemically or by means of heat. The treatment plants can operate continuously or batchwise.
Sterilization in the context of the present discussion includes the killing of microbes including bacteria and viruses so as to render them non-pathogenic, as well as the destruction of other biological agents that may cause harmful effects.
A typical thermal continuous biowaste sterilisation apparatus comprises a separating unit for solid matter, a storage tank, a heating unit and a dwell circuit as well as a circulation circuit for circulating biowaste through said heating unit and said dwell circuit.
Separation of solid matter from a biowaste suspension or slurry is necessary in order not to cause clogging of the system or excessive scaling of heat transfer surfaces. Biowaste slurries may contain considerable amounts of solids. As the separated solids also constitute a biological hazard, they must be separately and reliably sterilized, by way of e.g. heat treatment, before being disposed of.